Filter media
close Various porous materials used to intercept the solid particles contained in the fluid and support the filter cake in filtration operation. Commonly used filter media in industry include: ① woven materials, filter cloth and filter screen woven from natural or synthetic fibers, metal wires, etc., are the most commonly used filter media in industrial production. Such materials are cheap, easy to clean and replace, and the minimum particle size that can be retained is 5-65m. The single strand filter screen made of polyamide, polyester or polypropylene fibers has uniform texture, corrosion resistance and fatigue resistance, and is gradually replacing other fabric filter cloth. ② Porous solids include plain porcelain, sintered metal or glass, or porous plastic pipes bonded by fine plastic powder. The minimum particle size that can be intercepted by this kind of material is 1~3m, which is commonly used to treat suspension containing a small amount of small particles. ③ Accumulation media, such as sand, gravel, charcoal, diatomite and other granular materials, or glass wool and other non woven fiber accumulation layer. It is generally used to treat suspension with little solid content, such as urban water supply and sugar liquor to be purified. In addition, the industrial filter paper can also be used together with the above filter media to intercept a small amount of fine particles in the suspension. In recent years, the manufacture and application of polymer porous membranes have made great progress, which are used to filter smaller particles to obtain highly clear liquids. The membrane suitable for filtering 0.1~1m particles is called microporous membrane; The membrane suitable for filtering 0.01~0.1m particles is called ultrafiltration membrane (see membrane separation). Microporous membrane and ultrafiltration membrane are widely used in medicine, food, biochemistry and other industries. When selecting the filter medium, the content of solid particles in the suspension, the distribution range of particle size, the influence of the filter medium on the clarification degree of the filtrate and the filtration rate should be considered. In addition, the selection of filtration equipment, the corrosiveness of filtrate, and the temperature and pressure of filtration operation are also involved.